Method Of Preventing Loss Of Hydrocarbons To Atmosphere

Abstract

A self-contained vapor recovery system for gasoline service stations and for similar applications. Displaced hydrocarbon gases are collected at the point of entry when a vehicle's fuel tank is being filled, or when the service station's main storage tanks are receiving a fresh loading of gasoline. These vapors are collected under controlled pressure conditions and passed through a refrigerated condensation or absorption zone, and the liquid is returned to the service station's storage tankage, preferably below the liquid level there. The essentially hydrocarbon-free gas, now mainly air, is discharged into the atmosphere. The invention not only helps conserve a valuable natural resource, the petroleum from which the gasoline is made, but also alleviates air pollution or smog formation, since unburned hydrocarbons in the earth's atmosphere react under the influence of sunlight with nitrogen oxides and carbon monoxide from any source of combustion, to form a typical smog blanket.

Parent Case Text

This application is a continuation-in-part of application, Ser. No. 78,843 filed Oct. 7, 1970.

Description

BACKGROUND OF THE INVENTION

This invention relates to the field of prevention of air pollution. Specifically, it relates to a method of and apparatus for preventing loss of gasoline fractions when filling automobile fuel tanks and when refilling service station storage tanks.

When a motorist stops to refuel, he may take, typically, about 71/2 U.S. gallons, which means that 71/2 gallons of gasoline vapor are displaced during the refueling. Additionally, there is at least an equal evaporation loss due to agitation of the fuel, which may be warmer than the ambient temperature. This means that 15 gallons of vapor or 2 cubic feet of vaporized gasoline are lost to the air, and this is equivalent to around two-thirds pint of liquid gasoline or more than 350 grams of hydrocarbons per filling.

It is well known that "smog," now a major problem in most metropolitan areas, is presently attributable about 60 percent or more to the automobile population. Excluding CO.sub.2, automobile exhausts and evaporation losses contribute about 68,000,000 tons daily to the 142,000,000 tons of pollutants entering the nation's atmosphere daily. Automobiles powered by internal combustion engines emit into the atmosphere unburned hydrocarbons, nitrogen oxides, and carbon monoxide, which in various combinations react in the atmosphere under the influence of sunlight, causing a typical smog blanket.

The device of this invention, if installed at all service stations where auto gasoline tanks are filled and used according to the method of this invention, should substantially help in lowering the total quantity of hydrocarbons in the air.

It would also help conserve a valuable natural resource -- the petroleum from which gasoline is made. Additionally, over a period of time, savings at the service stations due to reduced losses of gasoline should pay for the necessary equipment.

The 350 grams of hydrocarbons lost into the atmosphere for each typical filling is a serious loss, for automobile emissions allowable by State and Federal laws are becoming stricter in efforts to combat smog, as indicated by the following tabulations:

TABLE I

PAST, PRESENT AND PROPOSED AUTO EMISSION STANDARDS--GRAMS PER MILE

Partic- % of Year Hydrocarbons CO NO.sub.X ulates Total pre 1963 Pre-1963 11.0 80.0 4.0 0.3 95.3 100 Calif.-1966 3.4 34.4 U U 41.7 44 Federal-1968 3.4 34.0 U U 41.7 44 Calif.-1969 2.2 23.0 U U 29.5 31 Federal-1970 2.2 23.0 U U 29.5 31 Calif.-1971 2.2 23.0 4.0 U 29.5 31 Calif.-1972 2.2 23.0 3.0 U 28.5 30 Calif.-1974 1.5 23.0 1.3 U 26.1 28 Calif.-1975 0.5 12.0 1.0 U 13.8 14 Federal-1975 0.5 11.0 0.9 0.1 12.5 13 U -- Uncontrolled CO -- Carbon monoxide NO.sub.x -- Nitrogen oxides

From Table I, the 1970 allowable emissions of hydrocarbons from a new automobile are 2.2 grams per mile. The filling loss incurred at a filling station for a typical filling, as noted in the example given above, is about 350 grams. This is equivalent to the maximum amount of hydrocarbons emitted to the air in about 160 miles of driving such vehicle. This may be more than that emitted in consuming 71/2 gallons, depending on the gasoline mileage of the vehicle concerned.

SUMMARY OF THE INVENTION

Briefly, a preferred form of my invention comprises a combination of the following elements:

1. a transparent flexible cup or a bubble in a transparent flexible tube to surround the discharge end of the gasoline dispensing hose to be held firmly against the body of the automobile around the gasoline tank filler spout;

2. means for maintaining a slight vacuum (about one-half of mercury or less below atmospheric pressure) within the cup or within the bubble and tube;

3. a tube attached to the cup or to the bubble and tube and operated under controlled light vacuum, such as one-half inch mercury below ambient atmospheric pressure, by means of a pressure control valve, and equipped with a mechanical device to supply the vacuum. Such a mechanical device may be similar to a commercial electric vacuum cleaner;

4. a device generally similar to Items 1, 2 and 3, placed on the unloading hose for the tank, truck or other vehicle delivering gasoline into the service station's storage tank or tanks;

5. a low temperature zone such as an insulated tank containing a cooling transfer medium. This may be a 50 percent mixture of ethylene glycol base anti-freeze in a water solution; the low temperature zone or bath is maintained well below the boiling point of the most volatile commonly-used hydrocarbon in gasoline, normal butane, which boils at 31.degree. F;

6. a condenser and trap (or condenser-absorber and trap) immersed in the low temperature zone or bath, with an inlet connected to receive vapors from the gasoline tank filling operation through the tube, and a vapor outlet from the trap (or from the condenser-absorber) connected to the vacuum source. The trap is equipped with a liquid level control device actuating a valve on the liquid outlet from the bottom of the trap;

7. an electric switch attached to the trigger actuating the gasoline delivery hose outlet valve for filling the automobile fuel tank. The switch is wired to actuate the pressure control device, in which the valve is normally in closed position, and to turn on the vacuum device while gasoline is flowing, and to turn off the vacuum device when the gasoline flow is stopped by release of the trigger, unless another dispensing pump is then operating; and

8. a pipe leading from the condensate trap valve into the main underground gasoline tank with a discharge near its lower end. Flow will normally be controlled by an electric pump actuated by the liquid level control device of Item 6 or may be by force of gravity, if the gradient permits.

The above combination thus (1) prevents the gasoline vapor displaced by the liquid gasoline during filling from escaping into the atmosphere, (2) prevents gasoline vapor from evaporating into the atmosphere during filling, (3) collects all the displaced and evaporated gasoline vapor and condenses it to liquid form, and (4) recovers the liquid. The invention thus prevents both pollution of the atmosphere and waste of valuable gasoline.

Other objects and advantages of the invention will appear from the following description of some preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a diagrammatic view in elevation and partly in section of a gasoline vapor recovery system embodying the principles of the invention.

FIG. 2 is a similar view of a modified form of system employing a refrigerated absorber-condenser in place of the simple condenser of FIG. 1.

FIG. 3 is a diagrammatic view in elevation and partly in section of a modified form of gasoline vapor recovery system also embodying the principles of the invention.

FIG. 4 is another diagrammatic view of a further modified system embodying the principles of the invention.

FIG. 5 is a view in elevation and in section of another modified system embodying the principles of the invention.

FIG. 6 is another diagrammatic view of yet another modified system of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a system which a filling station may use to practice the invention. An automobile 10 is being filled in the station. The automobile's fuel tank 11 has some liquid gasoline 12 in the bottom and gasoline vapor 13 above that. A filler tube 14 extends up from the tank 11 to a filler spout 15 adjacent an opening 16 in the body 17 of the automobile 10.

A filler hose 20 leads from the filling station's pump (not shown in FIG. 1) and its outlet end 22 is placed in the filler spout 15 after the closure cap (not shown) is removed. In the present invention, a transparent flexible cup 23 surrounds the outlet end 22 and is held firmly against the automobile's body 17 that is adjacent to the filler spout 15. The term "cup," as used herein to refer to the cup 23, includes a bubble in a transparent flexible tube, where the bottom portion of the tube fits around the filler spout and is firmly held against the body 17 of the automobile 10.

The cup 23 is fabricated of a hydrocarbon-resistant plastic, preferably semi-rigid and clear or transparent. Suitable materials are polyvinyl chloride and nylon, for example. The edges 24 of the cup 23 that contact the auto or other receptacle being filled are flexible and may be neoprene rubber or similar material. The contact sealing edge 24 need not be perfect, since only a controlled low sub-atmospheric pressure is desired. However, for safety reasons, it should be good enough to prevent inflammable or explosive gas mixtures -- i.e., avoidance of about one to seven percent hydrocarbons by volume admixed with air. The cup 23 is connected to a gas return tubing 25.

As a preferred means of preventing inflammable mixtures, should excessive air leakage occur, an instrument 50 may be incorporated to detect inflammability of the mixture in the return gas tubing 25, FIG. 1. This instrument 50 actuates a control valve 51 on a line 52 that is connected to a nitrogen storage tank 53, so as to dilute the mixture to below the limits of flammability. Such an instrument 50 is preferably based on the principle used in the Mine Safety or similar combustible gas detectors. In such an instrument 50, a metal filament enclosed in safety screen is connected as one arm of a Wheatstone bridge circuit, and any combustile gas in the surrounding atmosphere burns on its surface, raising its temperature and changing its resistance. This may read on an indicator scale, and by means of an electrical circuit and switch operate the nitrogen tank control valve 51.

By using a clear plastic cup 23 chances of an overfill by the operator are minimized. Ordinarily, a shut-off device stops the flow when the tank is full, but manual control often used to override the automatic shut-off device, can result in an undesirable overfill. For the same reason the return gas tubing 25, connected to the cup 23, should be flexible, clear, oil-resistant plastic, such as polyvinyl chloride, nylon, Tygon and similar materials. For sake of convenience, this tubing or vacuum hose 25 may be attached to and parallel with the gasoline delivery hose 20 for at least part of its length. The purpose of the transparent vapor line 25 and cup 23 is to reassure gasoline customers that the return line 25 is for vapor only. It thus acts as an impediment to pilfering by the station operator.

The cup 23 is connected by the tubing 25 to a suction device 26, such as a commercial vacuum cleaner system, so that at the cup 23 and in the tubing 25, the pressure is lower than the ambient atmospheric pressure, preferably about one-half inch of mercury lower, though the pressure difference may be greater (but less economical if it is) or lower (but less efficient than). A pressure controller 27 controls a suitable pressure control valve 28, and following that, there may be a desiccant 29. The desiccant 29 is used because the invention will not operate satisfactorily without it under atmospheric conditions where appreciable water is present. The desiccant device is located in the vapor line 25 ahead of the condenser, and preferably it should be in a replaceable cartridge. The desiccant may be any suitable low cost material such as silica gel, activated alumina pellets or the like.

The vacuum device 26 should have the capacity to handle at least two cubic feet per minute of vapors per pump expected to be operating at any given time, (including the storage tank 45 when it is being filled). For convenience a manifold may be arranged to handle several pumps operating at the same time, but connected to the same condenser, trap and vacuum system. Where more than one grade of motor fuel is sold it may be desirable to have separate systems discharging condensate liquid into separate main storage tanks.

The tubing 25 leads to a low temperature zone 30 comprising a tank 31 with insulated walls 32 containing a cooling transfer medium 33, such as a 50 percent aqueous solution of ethylene glycol or alcohol or other liquid that does not freeze at the lowest temperature of use, which may be about 10.degree. F. The tubing 25 is connected by a heat-exchange coil 34 to a trap 35. The liquid 33 may be cooled by a refrigerant coil 36 connected to a suitable refrigeration system outside the tank 30. A thermostat 37 may govern the temperature of the liquid 33. If desired, the coolant liquid 33 may be agitated (as in FIG. 2) by any suitable means, such as a pump or propeller, to improve the heat transfer. As an alternative, the refrigerant coil 36 may cool the tube 34 directly if the flow is restricted to a suitable small cross-sectional area to provide adequate heat transfer. From the trap 35 a tube 38 may conduct air and other gas that does not condense at about 10.degree. to 30.degree. F (and therefore is presumably free from the hydrocarbons present in gasoline) to the vacuum power device 26 and from there is safely exhausted to the atmosphere by the vent 39.

The trap 35 is provided with a liquid level controller 40 that electrically actuates a valve 41 enabling the condensed hydrocarbon liquid to flow through an outlet 43 from the trap 35 into a liquid return line 44 of oil-resistant material that leads to the storage tank 45, preferably the service station's main storage tank for gasoline, so that the condensate can be reused directly. In any event, the liquid return line 44 from the trap 35 to the storage tank 45 should normally discharge below the liquid level of the receiving tank 45, but as an alternate to gravity flow, a pump 46 may be used, located below the trap 35 to insure a head, and the pump 46 should be actuated by an electrical switch attached to the liquid level control device 40 for the trap 35.

An electrical switch 47 may be connected to the trigger 48 for the gasoline delivery hose and connected by a lead 49 to the vacuum device 26, to turn on the vacuum device 26 whenever gasoline is being delivered through the hose 20. A branch lead 49a goes from the lead 49 to the pressure control device 27, so that the pressure controller 27 is turned on when the gasoline is flowing and is turned off when the gasoline flow is stopped, except when there is gasoline flow from a different pump that is controlled by the same conduit 49 or a branch thereof.

Using the apparatus of FIG. 1, when the service station attendant starts to fill a vehicle's fuel tank he depresses the trigger 48 at the filling nozzle 21 to start the flow of gasoline. This actuates the switch 47 which turns on the vacuum device 26. As gasoline starts to flow, the displaced gas 13 and other gas from evaporation of gasoline 12 is collected by the cup 23 attached to the hose nozzle 20. Vacuum from the device 26 causes these vapors 13 to flow through the hose 25, the pressure control valve 27 and the desiccator 29, and to enter the condenser unit 30. The condenser coil 34 is surrounded by the coolant liquid 33 in the insulated tank 31, where the temperature is controlled at a convenient temperature such as 10.degree. F by the refrigerant flowing through the coil 36 and maintained at desired temperature by the thermostat 37. As liquid hydrocarbon condenses in the coil 34 it drips into the trap 35 where the level is maintained by the liquid level controller 40, which, in turn, actuates its outlet control valve 41, so that recovered liquid hydrocarbon gravitates or is otherwise transferred into the service station storage tank 45. Air and uncondensed gas from the trap 35 flow by the conduit 38 through the vacuum device 26, and are discharged into the atmosphere by the vent 39.

In areas where humidity is a problem, and also in most cases to take care of humidity due to rain, etc., the dryer tube 29 removes moisture, for moisture entering the trap 35 might form ice or solid hydrocarbon hydrates which might interfere with the operation of the valve 41.

Besides recovering vapor when filling auto gasoline tanks, the invention has other applications, such as larger portable "package" units to recover vapor when filling barges, vessels, tanks, tank trucks or cars; or even filling station tanks in case the service station system is not capable of handling both dispensing pumps and delivery trucks.

FIG. 2 shows essential parts of a refrigerated absorber-condenser column which may in some cases be more advantageous than the simple refrigerated condenser in FIG. 1. The collected vapors from the tubing 25, the pressure controller 27, the valve 28 and the desiccator 29 enter a low temperature zone 60 through a line 61 and are introduced into the bottom of an absorber 62. The absorber-condenser 62 may be a pipe fabricated of aluminum or other material with good heat transfer properties and filled with small (about one-half inch) Raschig rings, preferably of like material. Into the top of the absorber 62 a small stream of cooled absorption gasoline is pumped from a heat-exchange coil 63 immersed in the coolant 33. This gasoline is pumped from near the bottom of the main storage tank 45 by means of a submersible pump 64, which is actuated by the electrical switch 47 on the trigger 48 through a tube 65. The cooled absorption gasoline from the coil 63 enters the top section of the packed absorber 62 and is distributed over the Raschig ring packing by means of a circular perforated pipe 66. The diameter of the absorber 62 is such that adequate liquid-vapor contact occurs, but also such that liquid "flooding" does not occur at maximum expected vapor velocity. The absorption-cooling gasoline requirements are small-about 1 gallon per 100 cubic feet of vapor handled. The height of the absorber-condenser 62 need not be great -- about 6 feet should provide efficient recovery for this counter-flow, packed, refrigerated absorber-condenser. If desired, using insulation on the exposed section, the absorber 62 could extend above the insulated tank 67 of the low temperature zone 60. The gasoline liquid introduced at the top and the absorbed and condensed hydrocarbons from the vapors together gravitate to the bottom of absorber vessel 62 and drop into the liquid level-controlled trap 35, from where they are introduced into near the bottom of the main storage tank 45 through the line 44. Vent gas, essentially hydrocarbon-free, leaves the absorber 62 by the conduit 38, and the vacuum device 26 discharges it into the atmosphere through the vent 39.

In this modification, the coolant 33 is continuously stirred by a mechanical device, - e.g., a motor 68 and propeller 69 - in order to improve heat transfer.

It can readily be seen that the coolant volume contained in the tank 67 and the gasoline exchanger 63 may advantageously be over-sized to provide a "heat sink" for sudden heavy loads; i.e., when filling the storage tank 45 with about 9,000 gallons of gasoline during a 15 minute period. The vapor volume displaced and evaporated during this time may be about 2,400 cubic feet.

FIG. 3 shows a modified form of system of the invention usable by any service station selling gasoline. Here, a central refrigerated vapor condensing unit 30 (or a unit 60) of sufficient size is installed to discharge cooled liquid into the main storage tank 45 below the lowest level normally carried. In this form of the invention each pump 55 dispensing fuel to vehicles is equipped with a tube 25, and the main storage tank 45 has a refilling pipe 56 having a vapor line 57 returning vapor into the tube 25 and thence discharging into the low-temperature zone 30 (or unit 60). In this form of the invention, the controlled vacuum line leading from a suitably sized cup 58, generally like the cup 23 but bigger since the filler pipe 56 may be up to six inches in diameter, may conveniently be controlled by a manually operated valve 59.

FIG. 4 shows a further variation of the above in which a tight seal is made at the automobile gasoline tank filler pipe 70. A screw cap 71 the same size and similar in nature to the gasoline tank cap is fitted with a gasket 72 and sealed by a partial turn, as when putting the gasoline tank cap in place. Several standard adapters may be needed to fit all cars. A delivery hoze nozzle 73 is centered in this cap-sealing 71 device, and vents 74 release the vent gases displaced into an annular space 75 outside the delivery line 73 and enclosed by a closed vapor-tight cup or spherical unit 76, preferably made of semi-rigid transparent oil-resistant plastic, from which a vent line 77 goes to the storage tank 45 via the cooling device 30 (or 60). Similarly, the filler tube 56 for the storage tank 45 has a cup 78 and is connected to a delivery tank truck hose by a pipe union 79, when the cap 78 is removed. Vapors flow to the low temperature zone 30 from the union 79 by the tube 57 and tube 77. The cooling device 30 again may have the liquid level controller 40 and the trap 41. A desiccant or dryer tube 29 may again be provided where conditions are moist.

In the systems of FIGS. 4 and 5, since the vapors entering the main storage tank enter under slight pressure and are discharged below the liquid level, the gasoline stored (also usually at lower temperatures) in the tank acts as an absorbent for the vapors and lessens the load on the vapor recovery device.

It is also advisable to provide a vacuum-pressure relief safety valve 80 for the storage tank 45 or tanks to prevent inadvertent collapse or rupture of the vessel.

When vapors from the dispensing pumps or station storage tank or tanks are served by a single refrigerated condensing system as described, and actuated by a slight rise in pressure within such tank or tanks, there may also be included an inflatable bag 81, as shown in FIG. 5 made of gasoline-vapor resistant material (such as neoprene rubber), directly attached to the top of the storage tank 45 to temporarily capture and hold any vapor volume beyond the capacity of the condensing unit. Thus, this variation enables a smaller condensing system working more hours per day to be capable of handling sudden big overloads - such as would occur when a delivery truck is dumping gasoline into one of the storage tanks. These or any other excessive vapor overloads would go to the bag automatically and be processed later when the overload situation ceases.

In this variation, the neoprene or similar bag 81 could serve the entire service station storage comprising usually three or more underground tanks. A pipe manifold 82 leading directly from the top of each tank 45 would be used to fill or discharge vapors from the bag 81. The bag's capacity should be able to receive twice the vapor volume of the average expected tank truck delivery - perhaps as much as about nine thousand gallons, with a total displaced and evaporated vapor volume of about 2,400 cubic feet.

FIG. 6 shows a further variation of the invention using tight seals as in FIG. 4. In this form all vapors coming from filling the automobile tank 11 or other tanks are vented into near the bottom of the main storage tank 45 through the line 25 by a pipe 90. Similarly, when filling the main storage tank 45 with gasoline, discharge is into or near the bottom of the tank 45 by a pipe 91. Unlike other forms of the invention, this system operates under a slight pressure depending on hydraulic gradients and pipe friction losses. This pressure, while advantageous, is kept low for safety reasons, e.g., about 1 pound per square inch gauge, because of limitations imposed by strength of materials in the automobile gasoline tank 11 and by the design of the fuel system of the automobile. Therefore, a pressure relief valve 92 is provided in the pipe 25 for the auto gasoline tank vapors, preferably ahead of the drier 29, which may be placed either in individual collector lines or the manifold. Main storage tank vapors, now also including those from refueling automobiles, are discharged from the top of the tank 45 through a line 93 and thence through a perforated pipe 94 or any similar vapor distribution in the bottom of an insulated tank 95. Tank liquid gasoline is pumped from the tank 45 by means of the pump 64 through the line 65 into the insulated tank 95, in which the liquid level is controlled at or immediately above the outlet line 44 by a controller 96. Cooled and vapor-enriched gasoline, now increased in volume by the absorbed condensed hydrocarbons, is discharged from the insulated tank 95 by gravity or by a pump 98 into or near the bottom of the main storage tank 45. The temperature of the gasoline is controlled at the desired absorption-condensation temperature of about 10.degree. F by means of the temperature controller 37, which regulates the flow of refrigerant through the coil 36 and also turns on and off the refrigeration system as needed to maintain the desired temperature. Gasoline-free vapors are discharged from the vapor space in the insulated tank 95 by means of the outlet pipe 39.

Where the gradient permits, the pressure controller 96 and pump 98 may be omitted, as this is primarily a pressurized variation of the invention. In this system when using multiple pumps it may be desirable to provide a check valve 97 in the lines 25 in order to prevent backflow and loss of vapors through the pump dispensing systems when not in use. However, it is preferable to make the check valve 97 an integral part of the tightfitting screw cap shown as elements 71, 74, 75 and 76 of FIG. 4. In such case, the vents 74 are closed by a valve such as a flat plate forced by spring pressure in the direction of the member 71. When the screw cap is turned down upon the gasket 72, the valve plate is raised by pins which extend between the plate valve, and the flange of the filler neck at element 72, and are slightly longer than the thickness of the member 71 in the plane of the vents 74. The pipe 91 should be capped tightly to allow vapors above or below the limits set for the main storage tank to pass through a pressure-vacuum relief valve 80. In most cases, the relief valve 80 will not be required to function as sufficient venting will be accomplished through the line 93 and the vent 39.

In this form of the invention it is desirable to have the pump 64 actuated by the switch 47 connected to the trigger 48 as in FIG. 2. However, in a simplified system, this may be omitted and the submersible pump 64 may be manually controlled, if desired, since it normally will be pumping gasoline at a very low rate, such as 1 gallon per minute and may be operated continuously at low cost.

Thus, my invention comprises several embodiments providing:

A. A means of collecting vapors being generated by discharging gasoline into a tank (auto, storage or transport);

B. A visible means for checking against possible accidental loss or willful pilfering of any gasoline being delivered into a customer's tank;

C. A system for condensing the vapors generated and for collecting and returning the liquid so formed (by refrigeration and/or absorption); and

D. Means for temporarily storing excess vapors from sudden overloads, such as vapors to be handled when the condensing system is working temporarily at capacity.

The invention can be embodied as a service station "package" vapor recovery unit; for which the actual refrigerated condensing system for the system of FIG. 5 is relatively small -- sized for the average number of autos being refuled only -- yet capable of handling a large delivery of perhaps 9,000 gallons of gasoline from the refinery as a sudden 15 minute overload, the vapors from which would be temporarily stored in the inflatable, impervious, oil-resistant bag 81 for condensing at a later date. This bag 81 may be equipped and installed so that any natural condensation occurring therein (due to temperature change) gravitates back to the station's storage system.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

Claims

I claim:

1. A method for preventing pollution of the atmosphere by hydrocarbon vapors, comprising:

closing off a tank to be filled and a filling hose from access to the atmosphere during the filling of the tank,

collecting the gasoline vapors and air displaced from said tank by liquid gasoline and additional evaporated gasoline vapors during said filling of the tank,

demoisturizing the collected vapors, then condensing the collected vapors into liquid condition, thereby separating said air from said vapors, and

venting said air to the atmosphere in substantially vapor free condition.

2. A method for preventing escape of hydrocarbons to the atmosphere when filling an automobile's gasoline tank at a filling station, comprising:

sealing a connection between the gasoline filling hose and the automobile's gasoline tank,

withdrawing from the point of connection the gasoline vapors displaced by the liquid gasoline during the filling operation as well as any other gasoline vapors from the tank or hose,

cooling the withdrawn vapors to condense the hydrocarbons to liquid form, and

adding the liquid hydrocarbon to the liquid gasoline in the storage tank of the filling station.

3. The method of claim 2 wherein between the withdrawing step and the cooling step the hydrocarbon vapors are desiccated to remove water vapor therefrom.

4. The method of claim 2 wherein said withdrawing step is performed by exerting a below-ambient-atmospheric pressure.

5. The method of claim 2 wherein said cooling step includes absorbing the vapors by cooled gasoline drawn from the storage tank of the filling station.

6. A system for preventing loss of hydrocarbons to the atmosphere when filling a depleted automobile gasoline tank at a filling station having a fuel-dispensing tank and when filling the fuel-dispensing tank of the filling station, which comprises

means for collecting hydrocarbon vapors and air from the tank being filled under slight vacuum,

means for condensing said vapors to liquid form by a heat exchanger immersed in a refrigerated coolant, leaving said air substantially vapor free,

means for venting said vapor-free air to the atmosphere,

a collecting trap for the condensed liquid,

means for controlling the level in the collecting trap, and

means discharging the condensate back to the fuel dispensing tank.

7. The system of claim 6 additionally incorporating desiccating means for drying the hydrocarbon vapor before it enters the condenser.

8. The system of claim 6 wherein said means for collecting comprises a cup secured to the gasoline station's filling hose adjacent the nozzle thereof and capable of sealing against the body of the automobile adjacent the filling spout of the automobile's gasoline tank when the nozzle is inserted in said tank, and a conduit secured to said cup.

9. The system of claim 8 wherein the conduit is secured to said hose.

10. The system of claim 8 wherein said conduit is inside said hose.

11. The system of claim 8 wherein said conduit is transparent.

12. The system of claim 8 wherein said cup has a transparent main body.

13. The system of claim 6 wherein said means for collecting comprises a member secured to the gasoline station's hose surrounding its nozzle for attachment to the filling spout of said automobile's filling tank in the same manner as the normal closing cap thereof, and means for opening said member to the collecting system by attachment of said member to said filling spout, and for closing it off to the atmosphere when the nozzle is detached from the filling spout.

14. The system of claim 6 wherein said means for collecting comprises a member secured to the filling pipe of the service station's main storage tank in the same manner as the normal closing cap thereof.

15. A method for preventing loss of hydrocarbons to the atompshere when filling a depleted automobile gasoline tank at a filling station having a fuel-dispensing tank and when filling the fuel-dispensing tank of the filling station which comprises

collecting displaced hydrocarbon vapors and displaced air from the tank being filled,

simultaneously cooling, condensing, and absorbing said vapors into liquid form by direct contact and dispersion into a portion of the gasoline withdrawn from the fuel-dispensing tank, thereby refrigerating said portion to a suitably low temperature, and leaving said displaced air substantially vapor free,

venting said vapor-free air to the atmosphere,

introducing fuel-dispensing tank liquid into the refrigerated direct-contact zone,

maintaining a desired liquid level in the refrigerated direct-contact zone, and

adding the condensed-vapor-enriched liquid to the liquid gasoline in the storage tank.

16. The method of claim 15 wherein between said collecting step and the direct-contact-cooling step the vapors are desiccated to remove water vapors therefrom.

17. The method of claim 15 wherein said step is exerted at above-ambient-atmospheric pressure.